In general, a head-up display (HUD) is a device that shows vehicle information (e.g., speed, map, and indicator information) in front of a driver. The HUD improves the driver's attention to the road ahead, assisting in safe driving.
HUDs may be classified into a windshield type HUD and a combiner type HUD according to the forms thereof.
The windshield type HUD displays vehicle information on the window (windshield) at the front of a vehicle. The vehicle information may be displayed like a hologram at distance of about 2 m ahead of a driver. That is, the windshield type HUD displays the vehicle information on the windshield of the vehicle without a separate screen. However, the combiner type HUD displays vehicle information on a separate screen (glass) installed in front of the driver.
Since the windshield type HUD displays an image on the windshield of the vehicle, the position of an HUD screen may be somewhat adjustable according to the level of the driver's eyes. However, a polarizer film has to be included in the windshield to prevent image retention when an image is displayed on the windshield, and therefore a cost competitiveness of the windshield type HUD may be deteriorated. Furthermore, additional cost may be required to secure a package space in the crash pad (C/PAD) in front of the driver's seat.
The combiner type HUD is fixed to a specific position at the top of the crash pad. Therefore, a separate package space is not required, which leads to a reduction in cost. Consequently, the combiner type HUD is easy to apply to a low-priced vehicle. However, the combiner type HUD has problems in that an image can be focused on only a predetermined position and due to a narrow field of view, the driver cannot accurately view a screen even when the screen slightly deviates from the driver's view point.